文档介绍：Managing a Cisco work
Overview
The ponents of a Cisco Router
The Router Root Sequence
Managing Configuration Registers
Backing Up and restoring the Cisco IOS
Backing Up and Restoring the Cisco Configuration
Using Cisco discovery Protocol
Using
Resolving hostnames
work Connectivity
The ponents of a Cisco Router
Bootstrap
POST (power-on self test)
ROM monitor
Mini-IOS
RAM (random access memory)
ROM (read-only memory)
Flash Memory
NVRAM (nonvolatile RAM)
Configuration register
The Router Boot Sequence
1. POST - to verify ponents of the device are operational and present
2. Bootstrap – a program in ROM to look for and load the IOS (flash memory by default)
3. After the IOS is loaded, it will look for a valid configuration file stored in NVRAM (startup-config)
4. If startup-config file is in NVRAM, the router will load and run this file; otherwise start the setup mode
RAM for Working Storage
When router is turned on
bootstrap program executed from ROM
load Cisco IOS software into memory
Stores active configuration file, tables works map and routing address lists
Configuration file is in ASCII
Saved version in NVRAM
Operating system image in binary executable form
Command Executive
work Operating System
Programs
Active Configuration File
Tables
Buffer
Bootstrap Program Executes
RAM
Backup of Config. File
IOS
Interface
NVRAM
Flash
Boot Sequence in details
Power-up self test
Generic bootstrap loader executes from ROM
. source determined from the boot field of configuration register. Boot field indicates Flash work load, boot mands in configuration file indicates the exact location of image.
. image loaded into low-addressed memory. Hardware, ponents and lists on the console terminal
Saved configuration file in NVRAM is loaded into main memory, and execute one line at a time
If no valid configuration file exists in NVRAM, operating system executes a question-driven initial configuration routine